PTO-SCALAR-MODEL-AGU-ADDRESSING

1// PTO-UNIT: {"id":"PTO-SCALAR-MODEL-AGU-ADDRESSING","surface":"scalar","classification":["model","agu","addressing"],"depends_on":["PTO-SCALAR-MODEL-AGU-MEMORY"]}2// PTO-REQ-SCALAR-ADDRESS-001, PTO-REQ-MEMORY-COMPLETION-001: scalar addressing,3// pair preflight, and fault-suppressed register writeback.4
5pure func EffectiveAddress(base: Word, offset: Word, mode: AddressUpdateMode) => Word6begin7    if mode == AddressUpdate_PostIndex then return base;8    else return base + offset;9    end;10end;11
12func ExecuteScalarLoad(destination: GPRIndex, base_register: GPRIndex,13                       offset: Word, size_bytes: integer {1,2,4,8},14                       signed_load: boolean, mode: AddressUpdateMode)15begin16    let base = ReadGPR(base_register);17    let address = EffectiveAddress(base, offset, mode);18    let value = if signed_load then LoadSigned(address, size_bytes)19                else LoadUnsigned(address, size_bytes);20    if _LastFault == Fault_None then21        WriteGPR(destination, value);22        if mode == AddressUpdate_PreIndex || mode == AddressUpdate_PostIndex then23            WriteGPR(base_register, base + offset);24        end;25    end;26end;27
28func ExecuteScalarStore(source: GPRIndex, base_register: GPRIndex,29                        offset: Word, size_bytes: integer {1,2,4,8},30                        mode: AddressUpdateMode)31begin32    let base = ReadGPR(base_register);33    let address = EffectiveAddress(base, offset, mode);34    Store(address, size_bytes, ReadGPR(source));35    if _LastFault == Fault_None &&36       (mode == AddressUpdate_PreIndex || mode == AddressUpdate_PostIndex) then37        WriteGPR(base_register, base + offset);38    end;39end;40
41func ExecuteScalarLoadPair(destination_low: GPRIndex, destination_high: GPRIndex,42                           base_register: GPRIndex, offset: Word,43                           size_bytes: integer {1,2,4,8}, signed_load: boolean)44begin45    let base = ReadGPR(base_register);46    let address = base + offset;47    let second_address = address + NaturalToWord(size_bytes as integer {0..262144});48    let low_probe = ProbeDataAccess(address, size_bytes, size_bytes, FALSE);49    if RaiseDataAccessFault(low_probe, address) then return; end;50    let high_probe = ProbeDataAccess(51        second_address, size_bytes, size_bytes, FALSE);52    if RaiseDataAccessFault(high_probe, second_address) then return; end;53    let low_raw = LoadTranslatedUnsigned(low_probe.translated_address, size_bytes);54    let high_raw = LoadTranslatedUnsigned(high_probe.translated_address, size_bytes);55    let low = NormalizeLoadedValue(low_raw, size_bytes, signed_load);56    let high = NormalizeLoadedValue(high_raw, size_bytes, signed_load);57    RecordLoadEvent(low_probe.translated_address, size_bytes,58        low_raw, MemoryOrder_Relaxed);59    RecordLoadEvent(high_probe.translated_address, size_bytes,60        high_raw, MemoryOrder_Relaxed);61    WriteGPR(destination_low, low);62    WriteGPR(destination_high, high);63end;64
65func ExecuteScalarStorePair(source_low: GPRIndex, source_high: GPRIndex,66                            base_register: GPRIndex, offset: Word,67                            size_bytes: integer {1,2,4,8})68begin69    let base = ReadGPR(base_register);70    let address = base + offset;71    let second_address = address + NaturalToWord(size_bytes as integer {0..262144});72    let low_probe = ProbeDataAccess(address, size_bytes, size_bytes, TRUE);73    if RaiseDataAccessFault(low_probe, address) then return; end;74    let high_probe = ProbeDataAccess(75        second_address, size_bytes, size_bytes, TRUE);76    if RaiseDataAccessFault(high_probe, second_address) then return; end;77    let low = ReadGPR(source_low);78    let high = ReadGPR(source_high);79    StoreTranslated(address, low_probe.translated_address, size_bytes, low);80    RecordStoreEvent(low_probe.translated_address, size_bytes, low,81        MemoryOrder_Relaxed);82    StoreTranslated(second_address, high_probe.translated_address,83        size_bytes, high);84    RecordStoreEvent(high_probe.translated_address, size_bytes, high,85        MemoryOrder_Relaxed);86end;87
88pure func ScalarPrefetchAddress(base: Word, offset: Word) => Word89begin90    return base + offset;91end;92
93func ScalarPrefetch(base: Word, offset: Word, size_bytes: integer {1,2,4,8},94                    model: bits(5))95begin96    // Decode admits only the assigned L1/L2/L3 model values before sources are97    // read. Address formation is explicit, but no translation, permission98    // check, event, or memory effect is architecturally observed.99    - = ScalarPrefetchAddress(base, offset);100end;101